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A PRESENTATION

ON

RABIES

B Y

MARTINS NELSON OSAIGBOKAN UWAMOSECHIEF LIBRARIAN

DEPARTMENT OF ANIMAL AND ENVIRONMENTAL BIOLOGY

FACULTY OF SCIENCE, DELTA STATE UNIVERSITY, ABRAKA

JANUARY , 2013

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INTRODUCTION Rabies is an acute viral infection of the Nervous system caused by

Rabies virus. The virus is often transmitted to humans through the bite or lick of

fresh skin wound by a rabid animal (mostly dogs). Rabies virus, the agent of the disease is a member of the

Rhabdoviridae family (Genus: Lyssavirus); it is a single stranded, neurotropic, negative sense RNA virus (Albertini et al., 2006).

Rabies virus travels to the brain through the peripheral nerves causing acute encephalitis (inflammation of the brain) followed by paralysis and death in warm-blooded animals (man).

The incidence of Rabies virus infection per year in the world is estimated at 3.3 billion to 3.6 billion with approximately 55,000 death.

Rabies epidermis occurs in Asia, North and South America, and Africa.

3Fig 1. Map of the world showing the presence / absence of Rabies as at 2010Source: World Health Organization (WHO), 2010

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PROPERTIES OF RABIES VIRUSRabies virus is bullet shaped and has a protein coat with a lipid envelope. It’s outer surface is covered with thumb-like glycoprotein projections that are 5-10 nm long and 3 nm in diameter. The length of the virus averages approximately 780 nm (Albertini et al., 2006)

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Fig 2. Properties of Rabies virus Source: Albertini et al., 2006

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PATHOGENESISRabies infection is initiated in the victim on acquisition of the virus through the bite or direct saliva contact with infected animal. The virus then incubates at the site of inoculation replicating within muscle cells. After long incubation period, the virus enters the peripheral nerves and travels by retrograde axonal flow towards the Central Nervous System, first to the spinal cord then to the brain. Once in the brain, the virus travels by axonal flow down the trigemmal nerve to the salivary glands. The virus is found in the saliva (Drew WL, 2004, Beard M, 2001, Takayama N, 2005)

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EPIDEMIOLOGY/MECHANISM

Rabies virus is zoonotic, meaning it can be transmitted from one species to another such as dogs to humans commonly by an infected animal. The virus is found at the saliva of infected animals which show clinical signs; they excrete the virus through the saliva. Humans become infected through direct contact with infected animal saliva or when bitten.

Fig 3. Transmission of Rabies Virus

8Fig 3. Transmission of Rabies VirusSource: Google images

Fig 3a. Fig 3b.

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SYMPTOMSIt usually starts off like minor break down with symptoms of very high fever, headache, general weakness and discomfort.It progresses to acute pain, restlessness, depression, agitation, hyper salivation, increased sexual activity and hydrophobia.Finally, the patients may develop convulsions, muscles paralysis starting at the site of the bite or scratch, which will eventually leads to coma. Deaths usually occurs due to respiratory insufficiency 10 – 14 days after the onset of symptoms (Awoyomi et al., 2007, Takayama N 2005, Drew WL 2004).

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EFFECTS OF RABIESRabies disease is known to affect the spinal cord and the brain. This infection travels to the spinal cord and then to the brain through the peripheral nerves. Undiagnosed delayed or untreated Rabies causes acute encephalitis (inflammation of the brain), damage to the nervous system, muscles paralysis, and death (Drew WL 2004).

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DIAGNOSISA concrete diagnosis is made after laboratory test, that isolates the virus from the patient’s saliva or throat or corneal impression, skin biopsies and post-mortem tissue samples by Fluorescent Antibody Test (FAT) or by the Avidin-Biotin technique.

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Fig 2. Diagnosis of Rabies virus

Source: World Health Organization (WHO), 2005

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TREATMENT Treatment is by means of injections of rabies vaccines, antiserum and immunoglobulin which may prevent the virus from infecting if given with in 2 days. The incubation period for rabies enables effective treatment to be given, but if symptoms appear, they are treated with sedative drugs and analgesic drugs (Jackson AC 2008, DeMaria et al., 2010, Suzuki et al., 2008, Takayama, N., 2008, Adedeji et al., 2010).

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PREVENTION AND CONTROLPreventive and control measures include exposure of

vaccinated animal, immediate vaccination. Others include:Immunize all dogs and cats owned by an individual or by the community,Immunize any person with proven or probable exposure to rabies and administer rabies immunoglobulin in case of severe exposure (WHO 2005),Pounding and killing of stray dogs,Wild animals should not be kept as pets,Killing of wildlife around during an epidemic,Humans at high risk (e.g. laboratory personnel, professions at high risk) must receive pre-exposure immunization,People living or travelling to countries were rabies is endemic should be vaccinated with three doses of human diploid cell rabies vaccine (Adedeji et al., 2010),Strict quarantine regulations,Lastly, oral vaccines should be given to wild animals through bait. (WHO, 1997)

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CONCLUSIONRabies is a neglected disease of the poor and vulnerable populations whose deaths are rarely reported. It occurs mainly in rural communities where measure to prevent dog to human transmission have not been implemented. Eradication of rabies should be geared towards prevention, control and treatment. This could be achieved through health education, improvement of quarantine regulation and human and animal vaccination. It can be wiped out across the world if sufficient vaccinations are carried out on domestic dogs. If prompt medical care is available, rabies is uncommon in human beings but remains one of the most feared diseases.

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THANK YOUFOR YOUR TIME

Slide Prepared By Uwamose Martins